When designing ballistic armor for protecting, for example, a vehicle, consideration must be given to the type of projectile against which the armor must protect.
An important consideration which must be taken into account when designing ballistic armor is the weight per coverage area of the armor. Theoretically, armor can be constructed to protect against almost any threat or combination of threats. However, the resulting weight of the minor needed for such protection should be practical for the intended use. For example, when designing armor for vehicles such as trucks, armored infantry fighting vehicles, or armored personnel carriers, heavy armor will negatively impact the maneuverability and fuel efficiency of the vehicle, and will be more difficult to replace when necessary. Heavy armor can exceed the gross vehicle weight (GVW) set by the vehicle manufacturer and therefore cannot be used for such vehicle.
One type of threat is referred to as an explosively formed projectile (EFP). An EFP has a metal liner in the shape of a shallow dish with an explosive material behind it. When the explosive material is detonated the force of the blast presses the liner plastically into any of a number of configurations, depending on how the plate is formed and how the explosive is detonated. For example, the liner may be molded into a narrow rod, a “fist”, a plate (dish), or segmented rod.